21499839 has 6 divisors (see below), whose sum is σ = 31055336. Its totient is φ = 14333220.

The previous prime is 21499837. The next prime is 21499843. The reversal of 21499839 is 93899412.

It is not a de Polignac number, because 21499839 - 2¹ = 21499837 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21499794 and 21499803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21499837) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1194427 + ... + 1194444.

Almost surely, 2^21499839 is an apocalyptic number.

21499839 is a deficient number, since it is larger than the sum of its proper divisors (9555497).

21499839 is a wasteful number, since it uses less digits than its factorization.

21499839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2388877 (or 2388874 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 21499839 is about 4636.7918866389. The cubic root of 21499839 is about 278.0641942399.

The spelling of 21499839 in words is "twenty-one million, four hundred ninety-nine thousand, eight hundred thirty-nine".